Serum Markers of Immunity and Risk of Brain Tumors Evidence that a history of allergy and/or autoimmune diseases is associated with a reduced risk of gliomas in adults will be followed up in a case-control study of adult gliomas nested within 7 million United States military personnel with pre-diagnostic serum samples. We will quantify the dose-response relationship between risk of gliomas and levels of selected cytokines and growth factors and immune-related disorders in the subjects. Radiobiology Outreach The goal is to stimulate interdisciplinary interactions between the participants and to foster long-term research collaboration. It is expected that a monograph will be produced from the proceedings of the conference. Topics to be covered include the following: low dose, low-dose-rate effects;non-targeted radiobiological effects;radiation sensitive subgroups;dosimetry;in utero, occupational and environmental cancers;non-cancer diseases, such as thyroid, cataracts, cardiovascular disease;radiation risk and the public. Computed Tomography Organ Dose Calculations New tools and methods are being developed by using Monte Carlo transport technique to calculate organ dose for pediatric and adult patients undergoing computed tomography examinations. The organ dose estimates are being used for retrospective epidemiologic cohort and case-control studies. Radiotherapy Organ Dose Calculations New methods are being developed to reconstruct organ dose for patients treated by conventional (Co-60 and linear accelerator) and advanced (intensity modulated radiation therapy and proton therapy) radiotherapy techniques. The methods are used for dose comparison with conventional method, dose uncertainty study, and retrospective epidemiologic studies. Cancer Risks from CT Scan Use in the United States We are estimating the potential radiation-related cancer risks that may be related to current levels of CT use in adults, and also conducting radiation risk-benefit analyses for CT screening examinations. Early Life Radiation and the Risk of Child Cancer Studying radiation exposure during early life is of particular importance, given that many tissues are more susceptible to radiation effects in utero and at younger age of exposure. Results of our analysis, published in February 2011, showed some indication of a slight, non-significant increase in risk for all childhood cancer and leukemia with exposure to ionizing radiation in utero, and potential increased risk of lymphoma following exposure to x-rays in early infancy based on small numbers. Pediatric CT Examinations in Israel A cohort of 60,000 Israeli children who received CT examinations will be linked with the national cancer registry to estimate the risk of all cancers, especially brain and leukemia, associated with radiation exposure from these examinations. Pediatric CT Scans REB initiated an international cohort study of over 200,000 children to evaluate the potential risk of cancer associated with radiation exposure from pediatric CT scans. A comprehensive organ CT dose database for a total of 30 organs and tissues is being developed in support of a study of pediatric cancer risk and CT exposure. Pooled Analysis of Radiation-Related Brain Tumors Preliminary arrangements have been made to conduct a pooled analysis of the risk of radiation-related malignant and benign brain tumors, including data from studies worldwide that have information on radiation dose to the brain for individuals. Molecular and Histopathologic Clues to the Understanding of Thyroid Cancer Incidence Thyroid cancer incidence has increased significantly over the last few decades. We are evaluating whether alterations in molecular markers and histopathology of papillary carcinoma have changed over the last three decades, using thyroid tumor tissue collected from one US hospital. Molecular markers under investigation are BRAF, N-RAS, K-Ras, H-Ras, and RET/PTC. Pooled analysis of Radiation-Related Thyroid Cancer To improve our understanding of the etiology of thyroid cancer, REB scientists have set up an international consortium to study radiogenic thyroid cancer in children and adults. Statistical models of the radiation dose-response will be assessed as well as potential interaction with gender, age at exposure, attained age, and time since exposure.